Emptying the fuel tank to run race gas

[Chris Morales]

Please describe your procedure for emptying pumps gas from the tank if you have achieved good results on race gas. Specifically, if anyone has disconnected the fuel lines to truly drain the tank before adding race gas, please share your procedure.

I've seen a few descriptions here and there involving elaborate processes (e.g., driving until on fumes, adding race fuel, driving another 30 miles until once again on fumes, then adding race fuel). If this type of process is what it truly takes, that seems ridiculous and I'm not sure I have the appetite for it. Too much time and hassle just for an extra 30 hp.

Running fuel sufficient for a 100 tune is one thing (because you can have a mix with normal pump gas)...running fuel sufficient for a 104 tune is another.

[codrus]

When mixing octanes, you can just take the average of the two fuels.

1 gallon of 91 + 15 gallons of 100 == (1*91 + 15*100) / ( 1 + 15 ) == 16 gallons of 99.4 octane.

So the short answer is to drive until "0" miles remaining, then fill up with race gas. If paranoid, do this twice in a row and you'll have 16 gallons of 99.96 octane.

--Ian

[hmuller]

When mixing octanes, you can just take the average of the two fuels.

1 gallon of 91 + 15 gallons of 100 == (1*91 + 15*100) / ( 1 + 15 ) == 16 gallons of 99.4 octane.

So the short answer is to drive until "0" miles remaining, then fill up with race gas. If paranoid, do this twice in a row and you'll have 16 gallons of 99.96 octane.

--Ian

Never tracked my car so please take my comments with a grain of salt. Not sure everyone wants to fill up their tank with race gas at $9 a gallon. And if you do that at the strip the day you want to race you have all the extra weight from a full tank of gas. The cheapest method albeit labor intensive seems to be to drive until on fumes and add a little race gas for a few cycles. That way you are close to 100 octane with little extra weight in your tank.

[DGVR6]

I'm not sure on our reserve but Audi is usually conservative with DIS on 0.

My old s4 had about 1-2 gallons left on 0 miles.
You can continue to run a few more miles after its reach 0 then add race gas and run it a few more miles until you can smell that beautiful scent from the exhaust.

[HeelBuff]

Before I run the 104 octane program I fill up a 5 gallon gas tank with a flexi-hose and a stout screw top with MS-109 and put it on the back seat floor board and wedge it firmly in place by scooting the front seat back. Then I drive around the neighborhood until the car stalls from running completely out of gas. I coast to the side of the road and empty the 5-gallon jug. I drive home on the 93 octane tune (usually less than 1 mile) to be safe before I switch to the 104 octane map. As far as how far my car can go once the dash says "0 miles", it's easily between 20 and 30 miles. So I don't bother doing the procedure above until I've driven pretty far after 0 miles.

[mwmaroney1]

I've the 104 file multiple times without issues after just running 10-20 miles past 0 and then adding the 104 to the tank. I usually won't switch right away to the 104 map tho, I'll let it run through the lines for a little bit first.

Sent from my SM-G920V using Tapatalk

[DrBeerMD]

What that stud above me just said ^^^^^

[tonymission]

When I've done it I just ran it all the way down to 0, drove it some more really close to my house with some gas in a can and then let it run out of gas in my driveway.

[achan]

Are there any fuel pump issues running the tank dry?

[Djpeaksd]

Yeah maybe I'm wrong but I have always been told that running out of gas completely is not good for you car. Any thoughts? Sounds like some of you do it fairly often.

[HeelBuff]

Are there any fuel pump issues running the tank dry?

I've done it 5 or 6 times and the only issue I faced was the car throwing some codes. I used my APR app on my iPhone to clear them. I've let the car idle dry a couple of time in my driveway but it took longer than I wanted. When I make up my mind to put race fuel in the car I want it NOW and I am willing to terrorize the neighborhood with gas guzzling zero-to-speed-limit accelerations to get me empty quickly.

[Kirks5oh]

I've done it 5 or 6 times and the only issue I faced was the car throwing some codes. I used my APR app on my iPhone to clear them. I've let the car idle dry a couple of time in my driveway but it took longer than I wanted. When I make up my mind to put race fuel in the car I want it NOW and I am willing to terrorize the neighborhood with gas guzzling zero-to-speed-limit accelerations to get me empty quickly.

Pretty damn funny

[Princesur22]

I emptied my tank until about "0"then added 3 gallons of ms109 the performance of my car was crazy.but I did throw a code or 2 I also have emptied out my tank and had a mixture of E-85 and 93 octane